Movable barrier hydraulic braking

ABSTRACT

A hydraulic brake apparatus, a movable barrier apparatus, a hydraulic brake kit, a method of stopping movement of a movable barrier, and a method installing a hydraulic brake assembly are described herein. A selectively operable piston mechanism converts rotation of a drive shaft of a movable barrier into hydraulic pressure used to operate a brake configured to stop movement of the drive shaft.

RELATED APPLICATION

This is a divisional application of U.S. patent application Ser. No.13/330,009, filed Dec. 19, 2011, the contents of which are incorporatedby reference in their entirety herein.

FIELD

This invention relates generally to movable barriers and, moreparticularly, to braking assemblies for movable barriers.

BACKGROUND

Movable barriers known in the art can include braking systems. Thesebraking systems operate to stop and hold a movable barrier whencommanded or configured to do so. One type of braking system is anelectromechanical brake system. An electromechanical brake system can beconfigured to release when power is removed from the system or engagewhen power is removed, for example, to stop a barrier from dropping outof control due to the loss in power. In one example system, a barrier israised or rolled up to open a pathway and lowered or unrolled to closethe pathway. Uncontrolled dropping of such a barrier can result indamage to the barrier or surrounding structures. While anelectromechanical braking system is satisfactory for many purposes, thecomponents can be relatively large to provide sufficient brakingcapacity, which requires larger housings for movable barrier operatorsleading to increased manufacturing, packaging, and transportation costs.

SUMMARY

A brake apparatus for a movable barrier is provided that utilizes therotation of a movable barrier operator motor shaft or drive shaft toselectively apply a braking force to impede the rotation thereof. In oneform, a hydraulic piston mechanism is mounted radially adjacent to theshaft to selectively engage a cam mounted to the shaft. A brakemechanism is fluidly coupled to the hydraulic piston, such that thebrake mechanism is configured to impede rotation of the shaft inresponse to the hydraulic piston engaging the cam.

In another form, a movable barrier operator is provided having a housingand a motor at least partially disposed within the housing. The motorincludes a motor shaft and is configured to drive a movable barrierbetween open and closed positions. The operator further includes ahydraulic brake assembly that is at least partially received within thehousing and configured to selectively engage the motor shaft to therebyinhibit rotation of the motor shaft and movement of the movable barrier.

The hydraulic brake apparatus can further take the form of a kit for amovable barrier system including a movable barrier operator configuredto drive a movable barrier between open and closed positions. An examplekit includes a cam configured to be mounted to a shaft of the motor orthe movable barrier to rotate therewith. A hydraulic piston pump in thekit is configured to be mounted radially outward of the shaft toselectively engage the cam. The hydraulic piston pump is also configuredto be operably coupled to a brake mechanism included in the kit suchthat the piston pump engaging the cam causes the brake mechanism toengage the shaft to thereby impede rotation of the shaft.

By another approach, an example hydraulic brake device for a movablebarrier includes a hydraulic block housing that includes hydraulic linesand cylinders for the hydraulic components. The cylinders can beconfigured to be a piston pump, a reservoir/accumulator, a brake piston,and a spool valve. The hydraulic lines fluidly connect the cylinderswith the cylinder of the spool valve fluidly positioned intermediate ofthe piston pump and the reservoir. The spool valve includes a spoolmember received within the cylinder thereof that is shiftable betweenfirst and second positions. In the first position, the spool valveimpedes fluid flow between the piston pump and the reservoir, and in thesecond position, the spool valve allows fluid flow between thepressurized reservoir and the piston pump. The example hydraulic brakedevice further includes a brake mechanism with a shiftable brake pad, afirst piston for the piston pump, and a second piston for the brakepiston. The first piston is configured to be driven to an extendedposition by pressure within the reservoir when the spool member isshifted to the second position, so that the first piston can be engagedand driven by a cam to a compressed position. By the compression, afluid line connecting the piston pump to the brake piston ispressurized. The second piston within the brake piston is driven by thepressure in the line to an extended position to thereby shift the brakepad of the brake member to engage with a rotor.

A method of impeding rotation of a drive shaft of a movable barrier or amotor shaft of a movable barrier operator is provided to stop movementof a movable barrier coupled thereto. One example method includesconverting rotational movement of the shaft into linear movement of apiston within a piston pump. The operation of the piston pump createspressure within a hydraulic line fluidly connected to the piston pump.The pressure then drives a brake pad into frictional engagement with abrake member coupled to the shaft. By one approach, the pressure drivesa caliper piston to an extended position to engage and drive the brakepad.

A method of installing a hydraulic brake assembly for a movable barrieris also provided. One example method includes coupling a cam to a driveshaft of a movable barrier and mounting a piston pump adjacent to thedrive shaft for selective engagement of the cam. A brake member, such asa rotor, is also coupled to the drive shaft. The example method furtherincludes mounting a brake caliper assembly so that a brake pad thereofis positioned adjacent to the brake member for selective engagement ofthe brake member by the brake pad. A brake piston mechanism, with anestablished hydraulic line with the piston pump, is mounted adjacent tothe brake caliper assembly and is configured to selectively shift thebrake pad into engagement with the brake member.

BRIEF DESCRIPTION OF THE DRAWINGS

The above needs are at least partially met through provision of themovable barrier hydraulic braking described in the following detaileddescription, particularly when studied in conjunction with the drawings,wherein:

FIG. 1 is a perspective view of a portion of a structure defining abarrier opening therein having a rolling door assembly mounted adjacentthereto in a closed position;

FIG. 2 is a perspective view of components of a movable barrier operatorhaving a hydraulic braking apparatus according to various embodiments ofthe invention disposed therein shown through a cutaway of a housing ofthe operator;

FIG. 3 is a diagrammatic view of a hydraulic braking apparatus for amovable barrier according to various embodiments of the invention;

FIG. 4 is an exploded view of an example hydraulic braking apparatusaccording to various embodiments of the invention;

FIG. 5 is a perspective view of a hydraulic housing for the hydraulicbraking apparatus of FIG. 4;

FIG. 6 is a cross-sectional view of the hydraulic housing of FIG. 5taken along the line 6-6 in FIG. 5 having cross-hatching removed toclearly show the hydraulic lines and chambers therein;

FIG. 7 is a cross-sectional view of the hydraulic housing of FIG. 5taken along the line 7-7 in FIG. 5 showing detail of the piston pump;

FIG. 8 is a cross-sectional view of an example spool valve for thehydraulic housing of FIG. 5 showing the spool valve member in an offposition;

FIG. 9 is a cross-sectional view of the spool valve of FIG. 8 showingthe spool valve member in an operative position;

FIG. 10 is a cutaway view of a caliper piston and brake caliper devicefor the hydraulic braking apparatus of FIG. 4;

FIG. 11 is a flowchart for an example operation of a hydraulic brakingassembly in accordance with various embodiments of the invention; and

FIG. 12 is a flowchart for an example installation of a hydraulicbraking assembly in accordance with various embodiments of theinvention.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions and/or relative positioningof some of the elements in the figures may be exaggerated relative toother elements to help to improve understanding of various embodimentsof the present invention. Also, common but well-understood elements thatare useful or necessary in a commercially feasible embodiment are oftennot depicted in order to facilitate a less obstructed view of thesevarious embodiments. It will further be appreciated that certain actionsand/or steps may be described or depicted in a particular order ofoccurrence while those skilled in the art will understand that suchspecificity with respect to sequence is not actually required. It willalso be understood that the terms and expressions used herein have theordinary technical meaning as is accorded to such terms and expressionsby persons skilled in the technical field as set forth above exceptwhere different specific meanings have otherwise been set forth herein.

DETAILED DESCRIPTION

A hydraulic braking apparatus is provided that utilizes the rotation ofa motor or movable barrier drive shaft to impede rotation of the shaft.This configuration can be utilized to apply an increasing braking forcewith continued rotation of the shaft. The hydraulic braking apparatus isconfigured to selectively engage the shaft so that a movable barrieroperator can function normally to drive a movable barrier between openand closed positions. Then, when stopping movement of the movablebarrier is desired, the hydraulic braking apparatus can selectivelyengage the shaft. By the illustrated approach, a cam is mounted to theshaft and a piston pump is mounted radially adjacent to the cam. Whenbraking is desired, a piston of the piston pump is forced to an extendedposition by pressurized fluid from the reservoir in a path of rotationof the cam so that the cam, which is powered by the motor drive shaft,drives the piston to a compressed position. Pressure created inhydraulic fluid by the piston pump then causes a braking device toengage and impede rotation of the shaft.

So configured, the energy of the moving barrier is redirected to brakeand stop the barrier through the hydraulic brake. A controller can causeactuation of a portion of hydraulic brake to cause the brake apparatusto operate. By engaging a cam rotating with the movable barrier driveshaft, the movable barrier's motion (through the drive shaft) powers thebrake by compressing a hydraulic fluid, which in turn drives a brakeapparatus to engage the drive shaft. Such a brake can be made to have asmall size and readily incorporated into the movable barrier drivingapparatus. Moreover, the brake is not reliant upon an outside powersource to engage or stop the barrier such that the barrier movement canbe impeded in a variety of applications. These and other advantages willbe apparent in view of the following description.

Referring now to the drawings and especially FIG. 1, an example rollingdoor assembly 10 is illustrated. The rolling door assembly 10 isconfigured to be mounted to a wall or substrate 12 adjacent to anopening 14 to provide selective access therethrough. The rolling doorassembly 10 includes, at least in part, a rolling door 16 coupled to adrum 18 at a top portion of the rolling door 16 and guide rails ortracks 22 to direct movement of the rolling door 16 between open andclosed positions. The drum 18 can be generally cylindrical and include acircumferential perimeter and a central longitudinal axis L around whichthe drum 18 rotates to direct movement of the rolling door 16. Soconfigured, the rolling door 16 is movable to any position between aclosed position unrolled from the drum 18 and covering the opening 14and a stored or raised position rolled around the drum 18 and exposingthe opening 14. Movement of the rolling door 16 can be driven by, forexample, a movable barrier operator 24 or a manually-operated crank.Such an operator can be controlled by typical devices, including a pushbutton control unit, which can include an electronic controller and akeypad, or a remote control device that is configured to wirelessly sendcommand signals to a receiver in the operator.

More particularly, the rolling door 16, in this example, includes aseries of rectangular slats or panels 26. Each slat 26 rotatably couplesto adjacent slats along top and bottom edge portions 27, 29 thereof toform the main faces of the rolling door 16. As discussed above, therolling door 16 couples to the drum 18 along its top edge portion bysuitable attachment methods, such as hardware, welding, or the like. Byone approach, the drum 18 is hollow and connected to a shaft 28 by acoupling member 30. The shaft 28 can be a live shaft that, as known inthe art, rotates along with the drum 18, which can utilize a bearinginternal to an attached operator or crank. The shaft 28 canalternatively be a dead shaft that, as known in the art, remainsstationary during movement of drum 18 and uses an external bearingbetween the shaft 28 and the drum 18. The shaft 28 couples to mountingbrackets 32 that attach to the wall 12 by conventional methods. Themounting brackets 32 restrict the drum 18 from moving radially alongradii extending out and away from the longitudinal axis L. Similarly,the guide rails 22 mount to the wall 12 on adjacent sides of the opening14 in a conventional manner. The rolling door assembly 10 may furtherinclude a hood or cover 34 that at least partially surrounds andpreferably encloses the drum 18, and any portion of the rolling door 16wrapped therearound, therein. The hood 34 conceals the drum 18 and theportions of the rolling door 16 wrapped around the drum 18 and providesprotection for the rolling door assembly 10.

As shown in FIG. 2, an example hydraulic braking apparatus 100 for theabove described movable barrier system includes a hydraulic housing 102with a brake caliper device 104 mounted thereto. The housing 102includes all hydraulic lines, chambers, and cylinders necessary for thehydraulic operations of the hydraulic braking apparatus 100 therein.Moreover, the hydraulic operations of the housing 102 are configured, inpart, to engage the brake caliper device 104 to drive operation thereoffor impeding rotation of the shaft. The housing 102 is mounted to abracket 105 that is configured to be installed so that the shaft 28passes through a central opening 106 (FIG. 4) therein. As such, thehydraulic braking apparatus 100 is positioned radially adjacent to andoutward from the shaft 28. It will be understood that the shaft 28 canrefer to a drive shaft for the movable barrier 16 or a motor shaft.

As shown in FIG. 6, a cam 108 is mounted to the shaft 28 radially inwardof the hydraulic braking apparatus 100 so as to rotate therewith. Thecam 108 includes a bore 110 therethrough that is positioned off-centerso that with mounting of the cam 108 to the shaft 28, the cam 108 has anirregular path of rotation. If desired, the cam 108 can include abearing 112, such as a roller bearing or the like, mounted to a radiallyoutward portion of the cam 108 so that friction with componentsinteracting with the cam 108, and the wear associated therewith, isminimized. As shown, the cam 108 includes a radial, outwardly facingtrough 114 extending therearound for reception of ball bearings 116 ofthe roller bearing 112. Preferably, the shaft 28 includes a flattenedradial surface portion 118 and the cam opening 110 has a similarlyconfigured flattened portion 120, so that the cam 108 rotates with theshaft 28 without slippage or additional hardware or other attachmentmethods.

Referring now to the diagrammatic view of the hydraulic brakingapparatus 100 shown in FIG. 3, the operation will first be describedfollowed by details of the structure of each component. A piston pump122 includes a cylinder or chamber 124 and a piston member 126 slidinglydisposed therein. The piston member 126 shifts between an extendedposition where the piston member 126 extends partially out of thechamber 124 and a compressed position where the piston member 126 isfully received within the chamber 124. A control device, such as asolenoid 128, return spring 130, or the like, controls operation of thepiston pump 122 and is configured to drive or cause the piston member126 to be driven to the extended position. The piston pump 122 ismounted radially outward of the shaft 28 and the cam 108 mounted theretoso that with the piston member 126 in the extended position, an endportion 132 (FIG. 7) of the piston member 126 is located within a pathof rotation of the cam 108. So configured, when operation of thehydraulic braking apparatus 100 is desired, the control device 128drives or causes the piston member 126 to be driven to the extendedposition where the cam 108 subsequently impacts the end portion 132(FIG. 7) thereof and drives the piston member 122 to the compressedposition.

The hydraulic braking apparatus 100 utilizes hydraulic fluid 134 totransfer forces between its various components. As such, the piston pump122 includes an outlet 135 and an inlet 136 through which the pistonpump 122 expels and receives the hydraulic fluid. Check valves 138, orone-way valves, are mounted in-line with each of the outlet 135 andinlet 136 to control fluid flow therethrough. Utilizing this structure,the check valves 138 allow fluid to flow out of the piston pump 122through the outlet 135 and in through the inlet 136, but restrict theopposite flow.

A caliper piston 140 fluidly connects to the outlet 135 of the pistonpump 122 at a caliper piston line 142 to be driven thereby. The caliperpiston 140 includes a chamber or cylinder 144 and a piston member 146slidingly disposed therein to be driven between an extended brakingposition and a retracted rest position. As the pump piston member 126 isdriven to the compressed position, it pressurizes the hydraulic systemcausing the hydraulic fluid within the lines connecting the piston pump122 to the caliper piston 140 to exert pressure on the piston member 146of the caliper piston 140. With enough force, the piston member 146 isdriven to the extended position where it engages the brake caliper 104.The brake caliper 104 then frictionally impedes rotation of the shaft28.

The hydraulic brake apparatus 100 also includes a fluid reservoir oraccumulator 148 selectively fluidly coupled to the outlet 135 and theinlet 136 of the piston pump 122. The fluid reservoir 148 can beconfigured to hold excess hydraulic fluid to accommodate volume changesin the system and can aid in separation of air from the fluid. Moreover,as an accumulator, the reservoir 148 is configured to store energywithin the hydraulic system. This can be achieved using a spring, apressurized gas, or the like, and/or utilizing a piston or a bladder,for example. The check valves 138, in combination with the solenoid 128(or return spring 130, in the case of loss of energy), allow for thepreservation of energy in the accumulator 148 by controlling andrestricting fluid flow through the system. This pressurized fluid canthen be utilized to start operation of the hydraulic brake apparatus 100by driving the piston pump 122 to the extended position.

A pressure relief valve 150 can be installed between the piston pumpoutlet 135 and/or the reservoir 148 and can be configured to preventoverloading and/or rupture of the hydraulic lines or seals or shock tothe barrier system. The valve 150 can also be configured to maintain asmall positive pressure to exclude moisture and contamination.

The solenoid 128 is illustrated in FIG. 3 as stacked boxes illustratingconnections between the various lines of the hydraulic braking apparatus100. The upper box corresponds to the solenoid 128 being in an operativeposition that connects the reservoir 148 to the pump inlet 136 so thatthe pressurized fluid in the reservoir 148 can drive the piston pump 122to the extended position. The lower box corresponds to the solenoid 128being in an off position that connects the pump outlet 135 to thereservoir 148 and disengages the reservoir 148 from the pump inlet 136.

As shown in FIG. 3, the hydraulic braking apparatus 100 can also beconfigured to operate in a fire door system. Such a fire system isconfigured to shut a barrier in response to detection of a fire or otheremergency. This can advantageously restrict the spread of fire or otherundesired material. In order to operate in such a way, the hydraulicbraking apparatus 100 includes an alarm control device 129, such as asolenoid or a spring. The alarm solenoid 129 controls fluid flow betweenthe piston pump outlet 135 and the reservoir 148. The alarm solenoid 129is illustrated as in FIG. 3 as stacked boxes showing the two operationalstates of the solenoid. In a normal operating position, corresponding tonon-emergency situations, the pump outlet 135 and the reservoir 148 aredisconnected. In the engaged position, corresponding to a fire alarm orother emergency situation, the pump outlet 135 is connected to thereservoir 148 so that any pressure that is causing the caliper piston140 to engage the brake caliper device 104 is released and the hydraulicbraking apparatus 100 no longer impedes movement of the barrier 16. Assuch, the barrier 16 is allowed to move to the closed position coveringits associated barrier opening

Having described the general operation of the hydraulic brakingapparatus 100 above, the structural detail of an example apparatus 100will now be described with reference to FIGS. 4-10. As shown, thehousing 102 includes all of the hydraulic lines, passageways, andchambers/cylinders necessary for operation of the hydraulic brakingapparatus 100. The housing 102 includes a front surface 152, a rearsurface 154, a top surface 156, a bottom surface 158, and side surfaces160. It will be understood that directional orientation included in thedescription is for clarity purposes only and that the hydraulic brakingapparatus 100 can be mounted radially outward from the shaft 28 in anysuitable orientation with respect to the shaft 28.

In addition to the check valves 138 discussed above, the hydraulicbraking apparatus 100 utilizes a spool valve 162 that controls operationby controlling hydraulic fluid flow between the various brakecomponents. The spool valve 162 includes a generally cylindrical bore164 through the housing 102 extending from the top surface 156 to thebottom surface 158 thereof. The pump inlet 136, the pump outlet 135, thecaliper piston 140, the reservoir 148, and the pressure relief valve 150fluidly connect to the bore 164 so that the valve 162 can control thefluid flow therebetween. A spool member 166 having a generallycylindrical side surface 168 is slidingly disposed within the spool bore164. The spool member 166 includes four annular grooves 169 extendingtherearound generally transverse to the longitudinal length thereof thatdivide the spool member 166 into first, second, and third sections 170,172, 174 (FIGS. 8 and 9). The spool member side surface 168 in each ofthe sections 170, 172, 174 is recessed or concave with respect to thegrooves 169, so that when o-rings 176 are disposed in the grooves 169,the o-rings 176 sealingly engage the bore 164 to create first, second,and third volumes 171, 173, 175 (FIG. 8) between the bore 164 and thespool member 166.

Moreover, the spool member 166 includes a first bore 178 extendingtransversely to the spool longitudinal axis through the first section170 thereof and a third bore 180 extending transversely to the spoollongitudinal axis through the third section 174 thereof. A centrallongitudinal bore 182 extends from a bottom surface 184 of the spoolmember 166 past the third bore 180 and the first bores 178 tointernally, fluidly connect the first bore 178 and the third bores 180.The central bore 182 is sealed at the bottom surface, so that when thespool member 166 is disposed within the spool bore 164, the first volume172 and the third volume 176 are fluidly connected and sealed on the topand bottom thereof, and the second volume 173 is sealingly isolated.

With the single-piece housing form illustrated in the figures, thepassageways and chambers of the hydraulic components are bored into thehousing 102. As such, some of the passageways and chambers are open tothe front surface 152 of the housing 102. In order to contain thehydraulic fluid 134 within the housing 102, a cover or diaphragm 210 ismounted to cover the housing front surface 152 to thereby sealinglyclose any open passageways or chambers.

The housing 102 includes a concavely arcuate bottom right corner portion186 (FIG. 6) along the bottom surface 158 thereof. Preferably, thearcuate corner portion 186 has a radius of curvature equal to orslightly greater than a largest path of rotation of the cam 108, or thebearing 112 mounted thereto (i.e., the path of rotation corresponding tothe edge having the largest spacing from the cam bore 110). The pistonpump chamber 124 is bored into this corner portion 186 through thebottom surface 154 so that the pump piston member 126 can be drivenpartially out of the chamber 124 and into a path of rotation of the cam108. With this configuration, the cam 108 can pass closely adjacent tothe housing 102 with rotation of the shaft 28 to impact and drive thepiston member 126 of the piston pump 122 without undesirably contactingthe housing 102.

Turning now to details of the pump piston member 126, which includes theend portion 132 and a generally cylindrical top portion 188. The endportion 132 is preferably rounded, such as having a dome-shape, so as tominimize friction and potential wear caused by the cam 108 repeatedlyimpacting the piston member 126 during operation of the hydraulicbraking apparatus 100. The piston member top portion 188 includes a pairof transverse annular grooves 190 therearound, one adjacent to the endportion 132 and the other closely adjacent to a top surface 192 of thepiston member 126. The grooves 190 are sized and configured to receiveo-rings 194 therein. The o-rings 194 and piston member 126 are sized tosealingly engage the chamber 124 so that the hydraulic fluid isrestricted from leaking or otherwise passing between the o-ring 194 andthe pump chamber 124. Preferably, a side surface 196 of the pistonmember 126 between the grooves 190 is recessed with respect thereto oris at least partially concave so that there is a volume 200 between thepiston side surface 196 and the pump chamber 124 to receive thehydraulic fluid therein.

As discussed above, the pump chamber 124 includes the outlet 135 and theinlet 136 to fluidly connect the pump 122 to the other brake components.Referring now to FIG. 6, the outlet 135 is a bore that extends from anend portion 198 of the pump chamber 124. In the illustrated form, theoutlet 135 extends along the longitudinal axis of the chamber 124.

A check valve passageway 202 extends from an opening 204 in the housingfront surface 152 to fluidly connect to the pump outlet 135. At thefront surface 152, the check valve passageway 202 includes a chamber 206having a relatively wider diameter than the adjacent portion of thepassageway 202 to create a shoulder 208 for reception of the outletcheck valve 138. The check valve chamber 206 is sized to tightlyreceive, such as in a friction fit, the check valve 138 therein so thatthe hydraulic fluid driven from the piston pump 122 cannot bypass thecheck valve 138. In the illustrated single housing form, the check valvecavity 202 is bored into the housing front surface 152.

A recessed pump outlet-spool channel 212 in the housing front surface152 connects the check valve cavity opening 204 with an opening 214 of apump outlet-spool passageway 216. An opposite opening 217 of the pumpoutlet-spool passageway 216 opens to the spool bore 164. With the cover210 tightly secured against the housing front surface 152, the channel212 is water tight, and, as such, all of the hydraulic fluid driven bythe piston pump 122 through the check valve 138 is driven into the pumpoutlet-spool passageway 216 and into the spool bore 164. Operationaldetails of the spool valve 162 will be discussed in greater detailbelow. If desired, the channel 212 can include a wall 218 extending awayfrom the housing front surface 152 around its perimeter. With thisconfiguration, the cover 210 will deform over the wall 218 to provideadditional sealing area and protection against leaks.

Turning back to the piston pump 122, the pump inlet 136 extends from anopening 220 in the housing front surface 152 to intersect the pumpchamber 124 intermediate of the housing bottom surface 158 and thechamber end portion 198. Specifically, the pump inlet 136 opens to thepump chamber 124 to fluidly connect to the inlet volume 200, discussedabove, corresponding to the area between the member side surface 196between the o-rings 194. A recessed pump inlet-spool channel 222 in thehousing front surface 152 connects the pump inlet 136 with an opening224 of a pump inlet-spool passageway 226. An opposite opening 228 of thepump-inlet spool passageway 226 opens to the spool bore 164. As such,the pump inlet 136 is fluidly connected to the spool valve 162. Ifdesired, the channel 222 can include a wall 230 extending away from thehousing front surface 152 around its perimeter. With this configuration,the cover 210 will deform over the wall 230 to provide additionalsealing area and protection against leaks.

Additionally, the piston member 126 includes a longitudinal centralcavity 232 that opens at the piston member top surface 192, and, thus,to the pump outlet 135. A bore 234 extends through the piston member 126in a direction transverse to the pump longitudinal axis and opens to thepiston member side surface 196 between the grooves 190 to the inletvolume 200. The bore 234 also intersects the central cavity 232 so thatthe bore 234 fluidly connects the inlet volume 200 with the centralcavity 232, and therefore, the pump inlet 136 and outlet 135.Accordingly, the pump inlet 136 and outlet 135 are fluidly connectedboth within the pump 122 and through the spool valve 162.

The central cavity 232 further includes a check valve chamber 236 havinga diameter larger than a downstream portion of the central cavity 232 tocreate a shoulder 238 for reception of the check valve 138. Preferably,the chamber 236 has a diameter sized to tightly receive the check valve138 therein, such as in a friction fit, to allow fluid flow from theinlet 136 to the outlet 135, but to restrict fluid flow from the outlet135 to the inlet 136.

Turning now to details of the reservoir/accumulator 148, as shown inFIGS. 4-6. In the illustrated form, the reservoir 148 includes first andsecond cylinders 240, 242 bored into the housing 102 through the frontsurface 152 thereof. If desired or required by a particular application,an alternative number of cylinders can be used, such as one cylinder,three cylinders, or more. Each cylinder 240, 242 is sized to slidinglyreceive a cylindrical cap 244 therein. Each cap 244 includes an annulargroove 246 extending transversely therearound configured to receive ano-ring 248 therein. The groove 246 and o-ring 248 are sized to sealinglyengage each cylinder 240, 242 so that hydraulic fluid 134 disposed inthe reservoir 148 does not leak around the cap 244. A front end portion250 of each cap 244 includes a recess 252, which can preferably begenerally cylindrical as shown, sized to partially receive a spring 254.The spring 254 biases the cap 244 towards a rear surface 256 of thecylinder 240, 242. Thus, as the hydraulic fluid 134 is forced into thereservoir 148, the fluid 134 presses against the cap 244 and the cap 244is driven toward the housing front surface 152 deforming the spring 254.So configured, pressure can be stored in the reservoir in the form ofthe depressed spring 254.

In order to receive the hydraulic fluid 134 to store excess pressure inthe hydraulic system, the reservoir 148 is fluidly connected to thepressure relief valve 150 and the spool valve 162. The first and secondcylinders 240, 242 are fluidly connected by a passage 258 adjacent tothe rear surface 256 thereof opposite of the housing front surface 152.A reservoir passageway 260 has an opening 262 in the housing frontsurface 152 and is bored adjacent to the first cylinder 240 to a depthgenerally equal to the cylinders 240, 242. A second passage 264 adjacentto the cylinder rear surface 256 fluidly connects the first cylinder 240to the reservoir passageway 246.

A recessed portion 266 in the housing front surface 152 fluidly connectsthe reservoir 148, the spool valve 162, and the pressure relief valve150, as shown in FIG. 5. A reservoir-spool passageway 268 includes anopening 270 in the housing front surface 152 and extends to an opening272 to the spool bore 164. A pressure valve passageway 274 also has anopening 276 in the housing front surface 152 and an opening 278 to thespool bore 164. The pressure valve passageway 274 further includes apressure valve cavity 280 adjacent to the housing front surface 152having a diameter greater than an adjacent portion thereof forming ashoulder 282 for reception of the pressure valve 150. If required for aparticular pressure valve and as shown in FIG. 4, the cavity 280 can besized to tightly receive a pressure valve housing 283 therein, such asin a friction fit. The pressure valve housing 283 can then be configuredto receive and house the pressure valve 150 therein. As shown, thereservoir passageway opening 262, the reservoir-spool passageway opening270, and the pressure valve passageway opening 276 are all locatedwithin the recessed portion 266, and, as such, the recessed portion 266fluidly connects the components with the cover 210 mounted to thehousing 102. If desired, the recessed portion 266 can include a wall 284extending away from the housing front surface 152 around its perimeter.With this configuration, the cover 210 will deform over the wall 284 toprovide additional sealing area and protection against leaks.

Turning now to more details of the caliper piston 140, as shown in FIGS.4-7 and 10. The caliper piston chamber 144 includes an opening 286 inthe housing front surface 152 and an opening 288 in the housing rearsurface 154 so that the chamber 144 extends through the housing 102. Therear opening 288 has a relatively smaller diameter than the rest of thechamber 144 so that the chamber 144 includes a shoulder 290 extendingaround the rear opening 288. The caliper piston member 146 shown in FIG.4 includes a front cylindrical portion 292 with an annular groove 294extending transversely therearound configured to receive an o-ring 296.The front portion 292 and the o-ring 296 are sized to sealingly engagethe chamber 144 so that hydraulic fluid 134 is restricted from leakingtherearound. The piston member 146 further includes a rear cylindricalportion 298 having a relatively smaller diameter than the front portion292 sized to pass through the rear opening 288. The caliper piston 140utilizes a spring 300 that is configured and sized to fit around thepiston member rear portion 298. When the piston member 146 is disposedwithin the chamber 144, the spring 300 abuts a shoulder 302 of thepiston member front portion 292 adjacent to the rear portion 298 and theshoulder 290 adjacent to the rear opening 288 to bias the piston member146 away from the housing rear surface 154 and the opening 288 therein.

A recessed caliper channel 304 in the housing front surface 152 fluidlyconnects the caliper piston 140 to a caliper-spool passageway 306 havingan opening 308 in the housing front surface 152 and an opening 310 tothe spool bore 164. If desired, the caliper channel 304 can include awall 312 extending away from the housing front surface 152 around itsperimeter. With this configuration, the cover 210 will deform over thewall 312 to provide additional sealing area and protection againstleaks. The caliper piston 140 can additionally include a storage oroverflow chamber 314 bored into the housing front surface 152 that openswithin the recessed caliper channel 304. In this configuration, the wall312 would additionally extend around the chamber 314. The storagechamber 314 is sized to receive excess hydraulic fluid therein duringoperation of the hydraulic system.

Operation of the spool valve 162 will now be described with respect toFIGS. 8 and 9. The spool valve 162 operates by sliding the spool member166 within the bore 164 between an off position shown in FIG. 8 and anoperative position shown in FIG. 9. The pump outlet-spool passageway 216and the caliper-spool passageway 306 connect to the spool bore 164 in avertically stacked orientation closely adjacent to one another andadjacent to the housing top surface 156. These passageways 216, 306 areconfigured to fluidly connect with the spool first volume 171 in boththe operative position and the off position. As such, the pump outlet135 and the caliper piston 140 are continuously fluidly connected.Accordingly, if desired, the pump outlet 135 and the caliper piston 140could share a single spool passageway and a recessed front housingchannel configured similarly as discussed above if desired. The pumpinlet-spool passageway 226 connects to the spool bore 164 so as to befluidly connected with the spool second volume 173 in both the operativeposition and the off position, while the pressure valve passageway 274connects to the spool bore 164 so as to be fluidly connected with thespool third volume 175 in both the operative position and the offposition. Finally, the reservoir-spool passageway 268 connects to thespool bore 164 intermediate of and spaced from the pump inlet-spoolpassageway 226 and the pressure valve passageway 274. So configured, inthe operative position, the reservoir-spool passageway 268 is fluidlyconnected to the pump inlet-spool passageway 226 through the secondspool volume 173, and, in the off position, is fluidly connected to thereservoir-spool passageway 268 through the spool third volume 175.Additionally, as discussed above, the spool first and third volumes 172and 176 are fluidly connected through the spool bores 178, 180, 182.

With this configuration, when the hydraulic braking apparatus 100 isdisengaged with the spool member 166 in the off position, pressure builtup within the system is transferred to the reservoir 148 to be storedthereby, as discussed above, and the pump inlet 136 is isolated frompressure stored within the system by being isolated in the spool secondvolume 173. Then, when braking is desired, the spool member 166 isshifted downward so that the reservoir-spool passageway 268 transfersfrom the spool third volume 175 to the spool second volume 173. Thisallows reservoir pressure to transfer fluid stored within the reservoir148 to the pump inlet 136 and through the check valve 138 to above thepump piston member 126. This pressure drives the pump piston member 126to the extended position to be subsequently driven by the cam 106 to thecompressed position. When the cam 106 drives the pump piston member 126to the compressed position, the hydraulic fluid is driven through thepump outlet 135 and the spool valve 162 to overcome the spring 300biasing force and drive the caliper piston member 146 rearwardly so thatthe rear portion 298 thereof is driven through the rear opening 288. Byfluid connection through the spool valve 162, excess pressure can ventthrough the pressure relief valve 150, which, by virtue of the recessedportion 266 transfers fluid to the reservoir 148 and, if the spool valve162 is in the operational position, back to the pump inlet 136 to againdrive the pump piston member 126 to the extended position.

The hydraulic braking apparatus 100 can be pre-charged duringmanufacture, to a pressure range of about 30 pounds per square inch(psi) to about 50 psi, although other pressures can be used. Thepre-charge can be utilized to start operation of the hydraulic brakingapparatus 100 without prior engagement of the piston pump 122 with thecam 108, which allows the hydraulic braking apparatus 100 to staticallyhold against rotation of the shaft 28. The braking force required tostatically hold the movable barrier 16 in a stopped position is muchlower than the braking force required to dynamically stop rotation ofthe shaft 28. As discussed above, dynamic braking is achieved with thecam 108 engaging the piston pump 122. The pressure generated within thehydraulic braking apparatus continues to build up with repeated pistonpump operational cycles and as the shaft 28 rotates during its slowingdown. If the pressure exceeds a threshold pressure, the pressure reliefvalve 150 can vent the excess pressure to the reservoir 148 to keep themaximum pressure at a reasonable level, such as about 300 psi to about500 psi for the illustrated example.

The brake caliper device 104 will now be described with respect to FIGS.4 and 10. The brake caliper 104 includes front and rear surfaces 316,318 and mounts to the housing 102 so that the caliper front surface 316abuts the housing rear surface 154. The brake caliper 104 includes apair of brake pads 319 that are configured to impede rotation of theshaft 28.

In the illustrated form, the brake caliper 104 is secured with a screwor bolt 320 inserted through a threaded bore 322 extending through thehousing front and rear surfaces 152, 154 and into the brake caliper 104through the front surface 316 thereof. To keep the housing front surface152 flush, a front portion 324 of the bore 320 can have a relativelylarger diameter so that an end portion 326 of the bolt 320 configured tobe turned by a suitable tool can be received within the bore frontportion 324. In the illustrated form, the bore 322 is positioned in anupper left corner portion 328 of the housing 102 spaced from thehydraulic components and passageways therein.

As discussed above, the housing 102 and the brake caliper 104 securedthereto are configured to be mounted to the bracket 105, as shown inFIG. 2. Pursuant to this, the housing 102 and the brake caliper 104include bores 330 and 331 therethrough extending from the housing frontsurface 152 to the caliper rear surface 318. The bores 330 and 331 alignwith an opening 332 in the bracket 105 and an opening 334 in the cover210 to receive screws or bolts 333 therethrough. As such, the housing102 and the brake caliper 104 can be tightly secured against the bracket105 with the cover 210 therebetween. Preferably, the housing 102 issecured tightly enough so that the cover 210 seals the various recessedportions of the housing front surface 152 against leakage. With thehousing 102 mounted to the bracket 105, the springs 254 of the reservoir148 abut the cover 210 and the bracket 105 underneath to bias the caps244 rearwardly in the reservoir cylinders 240, 242 to pre-pressurize thesystem. In the illustrated form, the bores 330 are positioned in a lowerleft corner portion 336 and an upper right corner portion 338 of thehousing 102 respectively.

The brake caliper 104 includes a recessed portion 340 in the frontsurface 316 and onto a radially inward side 341 thereof. The recessedportion 340 is sized so that the bores 330 are positioned at ends 342thereof. A forwardly facing surface 344 of the recessed portion 340 hasone of the brake pads 319 secured thereto, such as with a suitableadhesive, hardware, or the like. Additionally, the brake caliper 104includes a free-floating brake pad member 346 that includes the otherbrake pad 319 secured to a rigid backing plate 348. An interior edge 350of the backing plate 348 abuts and is substantially complementary to aninterior surface 352 of the recessed portion 340 so that the backingplate 348 can be smoothly shifted therealong. An opposite outer edge 354of the backing plate 348 generally aligns with outer edges 356 of thebrake pads 319, so that the brake pads 319 are substantially aligned ina front to back relation. The brake pads 319 can preferably have agenerally identical shape and configuration. As shown, concave endportions 358 of the backing plate 348 are configured to extend partiallyaround the bolts 333 received in the bores 330 so that with the brakecaliper 104 mounted to the housing 102 and both secured to the bracket105, the brake pad member 346 is secured within the caliper recessedportion 340.

The brake caliper 104 is mounted to the housing 102 with the recessedportion 340 and the brake pad member 348 therein being alignedrearwardly of the rear opening 288 of the caliper piston 140. Soconfigured, when the caliper piston member 146 is driven rearwardly, therear portion 298 is free to pass through the rear opening 288 and toabut the brake pad member 346 thereby shifting the brake pads 319together to impede rotation of the shaft 28. If desired, the brake padmember 348 can be secured to the caliper piston member 146, such as byhardware, welding, or the like, so that the biasing force of the spring300 pulls the brake pad member 348 away from the other brake pad 319when the hydraulic braking apparatus 100 is off. This would additionallyrestrict the travel of the caliper piston member 146 within the cylinder144 despite the biasing force of the spring 300.

As shown in FIG. 2, a circular rotor 360 is mounted to the shaft 28 torotate with the shaft 28. The rotor 360 has a diameter sized to extendinto the recessed portion 340 of the brake caliper 104 between the brakepads 319. So configured, the caliper piston 140 can drive the brake pads319 together that then frictionally engage main surfaces 362 of therotor 360 to thereby impede rotation of the shaft 28.

Turning again to control of the hydraulic braking apparatus 100, thebracket 105 includes a tab 364 that is turned to be positioned adjacentto the right side surface 160 of the housing 102 and is configured tohave the solenoid 128 mounted thereto, such as with a solenoid mountingbracket 365. The solenoid 128 includes a shifting mechanism 366 thatshifts a bracket 368 vertically between a first lower position and asecond higher position. The solenoid bracket 368 is configured torotatably couple to a first end 370 of an arm 372. The arm 372 extendsover the housing 102 to a second end 374 thereof that is configured torotatably couple to an upper bracket 376 of the spool member 166. Apivot 378, such as a rod 382 extending between projections 380 on thehousing 102 and the brake caliper 104, extends through a transverse borein the arm 372, so that when the shifting mechanism 366 is in the lowerposition, the arm 372 holds the spool member 166 in the verticallyhigher off position. Then when operation of the hydraulic brakingapparatus is desired, the solenoid shifts the shifting mechanism 366 tothe higher position so that the arm second end 374 pivots downwardly toshift the spool member 166 downward to the operative position.

To protect against undesirable rotation of the shaft 28 in a case of aloss of power to the solenoid 128, the return spring 130 can be mountedbetween the arm 372 and an upper surface 384 of the solenoid 128 (or thesolenoid mounting bracket 365) in a depressed state. As such, when poweris lost and the solenoid 128 loses control of pivoting the arm 374, thespring 130 can force the arm 372 upward to engage the hydraulic brakeapparatus and thereby impede rotation of the shaft 28.

As shown in FIG. 2, the hydraulic braking apparatus 100 as describedabove, mounted to the bracket 105 can be mounted within the movablebarrier operator 24 so that the cam 108 and the rotor 360 are mounted toa shaft 386 of a motor 388 therein. In a preferred form, the motor 388is an electric motor. Alternatively, the hydraulic braking apparatus 100can be packaged as a part of a kit to be offered for sale, that isconfigured to be assembled and mounted to the substrate 12 adjacent tothe movable barrier opening 14. As such, the hydraulic braking apparatus100 can then be mounted so that the cam 108 and the rotor 360 aremounted to the drive shaft 28 of the movable barrier 16.

As known in the art, movable barrier operators can have travel limitsstored, such as in a memory therein, that correspond to open and closedpositions of the movable barrier 16. Then, when the movable barrierreaches these limits during travel, a signal is generated. Additionally,as known in the art, movable barrier operators can be configured to beresponsive to signals transmitted from a transmitter 390 (FIG. 1) to areceiver 392 in the operator, such as signals having codes matched in amemory of the operator, or signals transmitted from a wall mountedswitch device 394 (FIG. 1), having either a wireless or wiredconnection. The movable barrier operator 24 can also include a sensingdevice 396 as known in the art configured to sense movement of themovable barrier 16 when the motor 388 is not operational. This state canindicate that the movable barrier 16 is uncontrollably falling to aclosed position. In this instance, the sensing device 396 can beconfigured to generate a control signal indicating such undesirablemovement. Accordingly, the movable barrier operator 24 can include aprocessing or control device 398 configured to control operation of themovable barrier operator 24 in response to receiving signals as setforth above and cause the hydraulic braking apparatus 100 to becomeoperational to impede movement of the shaft 28 or 386 by sending acontrol signal to the solenoid 128 to shift the shifting mechanism 366to the higher position. Alternatively, the kit of the hydraulic brakingapparatus 100 can include a separate processing or control device 399configured to similarly send control signals to the solenoid 128.

With the structure described above, methods for operation andinstallation of the hydraulic braking apparatus 100 will be describedbelow. In a first example, a method 400 for operating the hydraulicbraking apparatus 100 is shown in FIG. 11. The method 400 includesconverting 402 rotational movement of the drive or motor shaft 28, 386into linear movement of the pump piston member 126 within the pistonpump 122. This can occur by the pump piston member 126 engaging the cam108 mounted to the shaft 28, 386. As discussed above, the pump pistonmember 126 can engage the cam 108 as a result of operation of the spoolvalve 162, such as by shifting the spool member 166 to the operativeposition. The pump piston member 126 can also engage the cam 108 byinitially pressurizing the reservoir 148 and releasing pressure withinthe reservoir into the piston pump 122 to drive the pump piston member126 to the extended position. Operation of the piston pump 122 creates404 pressure within the hydraulic lines fluidly connected to the pistonpump 122. With this pressure, the brake pad 319 is driven 406 intofrictional engagement with the brake member 360 coupled to the shaft 28,386.

One example method of installing 500 the hydraulic braking apparatus 100is illustrated in the flow chart shown in FIG. 12. The installationincludes coupling 502 the cam 108 to the drive or motor shaft 28, 386coupled to the movable barrier 16. The piston pump 122 is mounted 504adjacent to the shaft 28, 386 so that the piston pump 122 canselectively engage the cam 108. A brake member 360 is also coupled 506to the shaft 28, 386. The installation next includes mounting 508 thebrake caliper assembly 104 with the brake pads 319, as described above,adjacent to the brake member 360 so that the brake pads 319 canselectively engage the brake member 360. The brake piston mechanism 140is mounted 510 adjacent to the brake caliper assembly 104 so that thebrake piston mechanism 140 can selectively shift the brake pad 319 intoengagement with the brake member 360. Hydraulic lines, such as thosediscussed above, are then established 512 between the piston pump 122and the brake piston mechanism 140. Additionally, the installation 500can optionally include operatively coupling 514 the control device 398,399 to the piston pump 122 so that the control device 398, 399 cancontrol the selective engagement between the piston pump 122 and the cam108.

Those skilled in the art will recognize that a wide variety ofmodifications, alternations, and combinations can be made with respectto the above described embodiments without departing from the scope ofthe invention. For instance, although configurations, shapes, and sizesfor a hydraulic braking apparatus have been described, other suitableconfigurations, shapes, and sizes could also be utilized to achieve thedesired braking application. Such modifications, alternations, andcombinations are to be viewed as being within the ambit of the inventiveconcept.

What is claimed is:
 1. A hydraulic movable barrier brake apparatuscomprising: a cam coupled to a drive shaft of a movable barrier operatorconfigured to control operation of a movable barrier; a first pistonmechanism configured to selectively engage the cam; and a brakemechanism operatively coupled to the first piston mechanism andconfigured to impede rotation of the drive shaft through driving a brakecaliper in response to the first piston mechanism engaging the cam. 2.The hydraulic movable barrier brake apparatus of claim 1 furthercomprising a control device configured to control operation of the firstpiston mechanism.
 3. The hydraulic movable barrier brake apparatus ofclaim 2 further comprising a fluid reservoir fluidly connected to thefirst piston mechanism and configured to pressurize in response to thecontrol mechanism causing the first piston mechanism to disengage fromthe cam.
 4. The hydraulic movable barrier brake apparatus of claim 3further comprising a second piston mechanism fluidly coupled to thefirst piston mechanism and configured to cause the brake mechanism toimpede rotation of the drive shaft in response to operation of the firstpiston mechanism.
 5. The hydraulic movable barrier brake apparatus ofclaim 4 wherein the first piston mechanism, the second piston mechanism,and the fluid reservoir are hydraulically coupled by fluid lines, andwherein the fluid lines are defined by a single-piece housing.
 6. Thehydraulic movable barrier brake apparatus of claim 5 further comprisinga spool member disposed at least partially within the single-piecehousing and movable between on and off positions controlling a pluralityof fluid connections between the first piston mechanism, the secondpiston mechanism, and the fluid reservoir.
 7. The hydraulic movablebarrier brake apparatus of claim 3 wherein the fluid reservoir isconfigured to at least partially drive the first piston mechanism to anextended position to thereby engage the cam and be driven by the cam toa compressed position.
 8. The hydraulic movable barrier brake apparatusof claim 3 wherein the fluid reservoir includes a pre-charge pressurebetween about 30 psi and about 50 psi.
 9. The hydraulic movable barrierbrake apparatus of claim 2 further comprising a return spring configuredto drive the first piston mechanism to an extended position to therebyengage the cam and be driven the cam to a compressed position.
 10. Thehydraulic movable barrier brake apparatus of claim 9 wherein the returnspring is configured to drive the first piston mechanism to the extendedposition in response to a loss of power to the control device.
 11. Thehydraulic movable barrier brake apparatus of claim 2 wherein the controlmechanism comprises a solenoid.
 12. The hydraulic movable barrier brakeapparatus of claim 2 wherein the control mechanism is configured to:receive a signal indicating that the movable barrier traveled to amovement limit; and cause the first piston mechanism to engage the camin response to receiving the signal indicating that the movable barriertraveled to the movement limit.
 13. The hydraulic movable barrier brakeapparatus of claim 2 wherein the control mechanism is configured tocause the first piston mechanism to engage the cam in response tomovement of the movable barrier without operation of the movable barrieroperator.
 14. The hydraulic movable barrier brake apparatus of claim 1wherein the brake mechanism comprises: a rotor member coupled to thedrive shaft; and at least one brake pad positioned adjacent to the rotormember and configured to engage the rotor member to impede rotation ofthe drive shaft in response to operation of the first piston mechanism.15. A movable barrier operator comprising: a housing; a movable barriermotor at least partially received within the housing, the movablebarrier motor having a motor shaft and being configured to drive amovable barrier between and open and closed positions; a hydraulic brakeconfigured to selectively engage the motor shaft to thereby inhibitrotation of the motor shaft and movement of the movable barrier, whereinthe hydraulic brake assembly comprises: a cam coupled to a drive shaftof a movable barrier operator configured to control operation of amovable barrier; a first piston mechanism configured to selectivelyengage the cam; and a brake mechanism operatively coupled to the firstpiston mechanism and configured to impede rotation of the drive shaftthrough driving a brake caliper in response to the first pistonmechanism engaging the cam.
 16. The movable barrier operator of claim 15wherein the the brake mechanism comprises a brake pad and a rotorcoupled to the motor shaft, the brake pad configured to engage andimpede rotation of the rotor in response to the first piston mechanismengaging the cam.
 17. The movable barrier operator of claim 16 whereinthe hydraulic brake assembly further comprises a second piston mechanismconnected between the first piston mechanism and the brake mechanismsuch that operation of the first piston mechanism drives operation ofthe second piston mechanism and the second piston mechanism drives thebrake pad into engagement with the rotor.
 18. The movable barrieroperator of claim 15 further comprising a control device configured tocontrol operation of the motor and the hydraulic brake assembly.
 19. Themovable barrier operator of claim 18 wherein the control devicecomprises a solenoid configured to selectively cause the first pistonmechanism to engage the cam.
 20. The movable barrier operator of claim15 further comprising a fluid reservoir having a cylinder disposedwithin the housing and configured to receive hydraulic fluid in responseto the first piston mechanism disengaging from the cam.
 21. The movablebarrier operator of claim 15 further comprising a return springconfigured to cause the first piston mechanism to engage the cam andimpede rotation of the motor shaft in response to a loss of power.
 22. Ahydraulic movable barrier brake apparatus comprising: a cam coupled to adrive shaft of a movable barrier operator configured to controloperation of a movable barrier; a first piston mechanism configured toselectively engage the cam; a brake mechanism operatively coupled to thefirst piston mechanism and configured to impede rotation of the driveshaft in response to the first piston mechanism engaging the cam; afluid reservoir fluidly connected to the first piston mechanism andconfigured to pressurize in response to the control mechanism causingthe first piston mechanism to disengage from the cam; a second pistonmechanism fluidly coupled to the first piston mechanism and configuredto cause the brake mechanism to impede rotation of the drive shaft inresponse to operation of the first piston mechanism; a housing definingfluid lines hydraulically coupled to the first piston mechanism, thesecond piston mechanism, and the fluid reservoir; a spool memberdisposed at least partially within the housing and movable between onand off positions that selectively control a plurality of fluidconnections among the first piston mechanism, the second pistonmechanism, and the fluid reservoir.
 23. The hydraulic movable barrierbrake apparatus of claim 22 wherein the brake mechanism comprises abrake pad and a rotor coupled to the motor shaft, the brake padconfigured to engage and impede rotation of the rotor in response to thefirst piston mechanism engaging the cam.
 24. The hydraulic movablebarrier brake apparatus of claim 22 further comprising a control deviceconfigured to control operation of the hydraulic brake assembly byeffecting selective movement of the spool member.
 25. The hydraulicmovable barrier brake apparatus of claim 22 further comprising a fluidreservoir having a cylinder disposed within the housing and configuredto receive hydraulic fluid in response to the first piston mechanismdisengaging from the cam.
 26. The hydraulic movable barrier brakeapparatus of claim 22 further comprising a return spring configured tocause the first piston mechanism to engage the cam and impede rotationof the motor shaft in response to a loss of power.
 27. The hydraulicmovable barrier brake apparatus of claim 22 wherein when disposed in theoff position, the spool member effects a connection of the fluid linesto fluidly disconnect a fluid pump from the fluid reservoir and tofluidly connect the fluid reservoir to a pressure relief.
 28. Thehydraulic movable barrier brake apparatus of claim 22 wherein whendisposed in the on position, the spool member effects a connection ofthe fluid lines to fluidly connect a fluid pump to the fluid reservoirand to fluidly disconnect the fluid reservoir from a pressure relief.